Despite their disproportionate vulnerability to HIV and Hepatitis C (HCV), incarcerated women are rarely the focus of prevention research. At risk women can be difficult to reach in the community; so prison provides a unique opportunity to gain access to women while they have the time available to engage in prevention programming and are not preoccupied by other immediate needs (e.g. childcare, shelter, next meal, drug acquisition). Since the vast majority of women in prison will soon return to their communities (Travis, 2005), their elevated infection rates also carry serious public health implications. Recent meta-analyses of interventions in HIV prevention have demonstrated that current risk behavior models must be adapted to effectively fit the needs of distinct populations. Since very little research has been conducted with incarcerated women, formative research is needed to establish which factors are most influential in their risk behavior so that these factors can be targeted through interventions. The proposed research involves a mixed-methods study to evaluate a model of risk behavior among incarcerated women based on Social Action Theory (SAT). Expanding upon classic social-cognitive theories, SAT emphasizes two major components: (1) the dynamic health action state; and (2) the self-change process; and incorporates contextual factors like interpersonal dynamics and internal affective states. In the current study, qualitative in-depth interviews with incarcerated women (N = 20) will be used to examine the dynamic health action state, which includes interdependence with a sexual partner and experienced consequences of action taken. Quantitative data collected in structured surveys with incarcerated women (N = 200) will be used to test the self-change process, specifically looking at pathways that incorporate the impact of established cognitive predictors of risk behavior, as well as intimate relationship control and psychological distress, on sexual risk-taking. This study will be the first step in a program of research ultimately leading to the design of a comprehensive intervention that integrates mental health treatment and risk prevention to be administered within correctional settings. The applicant, a top student at the #1 clinical psychology program in the country, has already obtained the support of prison and state department administrators. She has also assembled a team of experts who have devised a comprehensive training plan for the applicant, and are eager to assist in achieving the fellowship goals.